NR SA Paging Issue

Paging Issue Check Points 
                       Some check points which will help you to analyze the root cause .

Channel to Check :
                   PCCH -> PCH -> PDSCH  

Check points:

• RLC TM
• P-RNTI ->16bit (‭65534‬-> FFFE)-> Can be seen in PDCCH channel 
• Paging Message will go on DCI Format 1_0 always -> Can be seen in PDCCH channel
• DCI payload check (will update ASAP) 
• Timer T3513
• 5G-S-TMSI value from Registration Accept message ->fiveGGUTI-> last 6 Bytes 
• Spec 23.003  sec 2.11
• PDCCH Transmission for paging can share the same search space as PDCCH transmission for SIB1 in case of Multiplexing pattern3->Can be seen in PDCCH channel 
• In SIB1 - > pagingSearchSpace == '0’  It mean that paging and SIB1 share the same search space

Addition Information :

• Transmit Paging information to a UE in RRC IDLE mode or RRC_INACTIVE mode
• if the RRCRelease message  with all IE' s Omitted -> RRC_IDLE Mode 
• if the RRCRelease includes suspendConfig->RRC_INATIVE Mode
• Full -RNTI(I-RNTI) which was allocated to the UE within the RRC release message when moving the UE to RRC Inactive
•  The ShortI-RNTI-Value IE is used to identify the suspended UE context of a UE in RRC_INACTIVE using fewer bits compared to I-RNTI-Value(24bits)
• There is a requirement to notify UE of a change to the System information or an incoming ETWS/CMAS message , in this case Paging procedure does not use RRC paging message , instead payload of PDCCH (DCI 1_0 ) will decode with Short Messages flag 
• Difference between LTE Paging and NR paging is : 5G Paging procedure does not allow a UE to be Addressed using its IMSI
• In LTE - >UE_ID = IMSI mod 1024 Whereas,
• In 5G ->  UE_ID = 5G-S-TMSI mod 1024
• 5G-S-TMSI value and Paging IE reference 

• PDCCH Transmission for paging can share the same search space as PDCCH transmission for SIB1 in case of Multiplexing pattern3
• In SIB1 - > pagingSearchSpace == '0’  It mean that paging and SIB1 share the same search space
• Example Scenario :
• RRC Idle mode 
• Paging
• 5G_S_TMSI == '000101010010010100110101000100000010000000110000'
• amfSetId-> 0001010100
• amfPointer-> 100101
• 5G_TMSI-> 00110101000100000010000000110000
• RRCSetupRequest 
• Include ue_Identity->  ng_5G_S_TMSI_Part1 == '010010100110101000100000010000000110000'
• Include establishmentCause == 'mt_Access'
• ng-5G-S-TMSI-Part1->The rightmost 39 bits of 5G-S-TMSI(38.331 Spec)
• RRCReject 
• Paging
• 5G_S_TMSI == '000101010010010100110101000100000010000000110000'
• RRCRequestSetup 
• RRCSetup
• RRCSetup complete 
• include 5G_S_TMSI_Part2 == '000101010'
• ng-5G-S-TMSI-Part2->The leftmost 9 bits of 5G-S-TMSI(38.331 Spec)
• PF and PO will be shared Soon.